U.S. Pat. No. 4,618,060 to Tarter granted Oct. 21, 1986 relates to a floppy disk casing or envelope with optional write protect capability and shows a variety of devices intended to cooperate with the envelope to be selectively displaced to permit or deny writing upon a disk. The Tarter devices slide within an edge of the disk envelope to cover or uncover a notch therein and thereby block or not block mechanical and/or optical sensing means which in turn disable or enable write head circuits, allowing the memory disk within such casing to be selectively written upon.
The approach in the Tarter patent distinguishes over other such write protect devices which are, in essence, "built in" to floppy disk packages, one such being shown in U.S. Pat. No. 4,549,240 to B. A. Hedges granted Oct. 22, 1985, and another being shown in U.S. Pat. No. 4,536,812 to K. Oishi et al. granted Aug. 20, 1985. A concept similar to that of the Tarter invention is shown in U.S. Pat. No. 4,521,820 to J. D. Fan issued June 4, 1985, which allows modification of a floppy disk package to provide write protection by selective movement of an element to cover the disk notch.
In both the Tarter and the Fan concepts, the write protect constructions rely for their utility upon the particular construction of the disk envelope; namely, that the outer edge of the envelope be so constructed as to provide a channel into which the write protectors thereof can be positioned for sliding movement within the disk package, between its outer covering walls.
A wide variety of floppy disk packages having envelopes of a wide variety of constructions have evolved and are now being utilized. Many of these do not include the constructional details of the earlier mentioned patents and therefore have no utility with respect thereto. These include many designs wherein there are no embossments or wells to establish defined channels within the disk envelope.
Accordingly, it is an object of the present invention to provide a method, tool and article of manufacture enabling write protection to be added to a wide range of floppy disk package envelope constructions wherein there is no particular channel defined by the edges thereof. It is a further object of the invention to provide a method, tool and article which can be applied to existing disk envelope designs after manufacture and by a disk user in a simple, inexpensive and reliable manner. It is yet a further object to provide a method and technique for modifying disk package envelopes by the simple expedient of punching a slot therein, which slot enables the addition of a write protector which is readily applied by user.
It is the final object of the invention to provide an improved method and article for providing write protection for floppy disks and the like not restricted by present disk manufacturing and constructional detail.